A former director at Charterhouse Capital has told a London court how he "got mugged" by the private equity group, which he has taken to court over a disagreement on the value of his shares in the firm.

Geoffrey Arbuthnott alleges the firm's executive chairman Gordon Bonnyman and 16 other current and former Charterhouse shareholders tried to force him to sell his entire stake in the firm for £1.35 million in November 2011.